Diabetes-related vascular disease is one of the major health problems. Knowledge is incomplete concerning the factors contributing to the development of macro- and micro-vascular complications. The National Diabetes Board, in 1980, emphasized the need for a prospective study on a homogeneous population to investigate the role of various risk factors in the excessive vascular complications that attend diabetes. The proposed research closely follows the recommendation. The objective of this research is to study the relationship between diabetes and various macro- and microvascular complications, using a prospective approach, on the Oklahoma Indians - a population with high prevalence of diabetes and its complications. Factors distinguishing subjects who will and who will not develop these complications will be identified. In addition, various morbidity and mortality rates in the diabetic will be estimated and compared with those in other populations. Detailed baseline data on 1085 diabetic subjects collected in 1973-78 are available. The extensive data is a unique and important resource as basis for a 10-year prospective study. As the largest contributor, the study will also add considerable power to the WHO Multinational Study of Vascular Disease in Diabetes. With the extensive data base, the research permits, at a relatively modest cost, a timely and significant prospective study of vascular disease in diabetes.